The Wildcats stifled the Cougars 60-25 in their Pac-12 opener Thursday night.
It was Washington State's lowest-scoring game since the Cougars scored 25 points at Idaho on Jan. 15, 1938, and the lowest-scoring game ever for a team at McKale Center.
"They did a good job shutting us down," the Cougars' D.J. Shelton said in a major understatement.
The previous McKale record for fewest points was 37 by Northern Arizona in 1989.
Lacy was out after undergoing an emergency appendectomy last Saturday. Washington State was also without starter Dexter Kernich-Drew because of a concussion, but Cougars coach Ken Bone wasn't making excuses.
"Arizona jumped on us early and it never really ended," he said. "We weren't playing an up-tempo game but a lot of that was due to Arizona's defense. All the credit goes to Arizona and how solid they are in different areas of defending on and off the ball."
Wildcats coach Sean Miller said the low score was due to a combination of Washington State's depleted lineup and Arizona's defensive performance.
"We know that they were playing short-handed," Miller said. "Having said that, I thought our defensive effort was outstanding. .... It's a little bit of both, probably not as great a defensive effort as the score would reflect. At the same time I think we leave here feeling good about what we were able to accomplish."
The Wildcats (14-0, 1-0) took a 21-2 lead and were up 28-7 at halftime.
The Cougars (7-6, 0-1) shot 9 for 45 from the field and they needed to make a series of shots late to reach that.
Junior Longrus led the Cougars with six points.
"It was different because you don't see many games like this," Arizona's Nick Johnson said.
Kaleb Tarczewski, back after missing two games with a sprained ankle, scored 11 points and was the only player for either team to reach double figures.
Washington State's nine field goals were also a McKale record, breaking the previous mark of 13, also set by Northern Arizona in that 1989 game. So was the Cougars' 20 percent shooting, breaking the mark of 20.3 percent set by NAU that night 24 years ago.
The Cougars missed their first 16 shots before Royce Woolridge made a layup with 6:42 left in the half. Arizona led 21-2 on Johnson's 3-pointer with 8:18 to go until the break.
"They are really a good team," Woolridge said. "It's just hard to score on them. They're big in the paint and it was just really had to score because they were so active. It's a good learning experience, though, and we won't let this happen again."
Washington State made it 21-7 before the Wildcats scored the final seven points of the half.
The Cougars were 2 of 20 from the field in the first half, breaking the McKale record of four field goals set twice, most recently by Arizona State in 1991. It was also a record for fewest points by a team in a half and fewest combined points in a half. The old record was 37 against Oregon in 1985.
The 9.5 percent shooting percentage was also an arena record for a half.
Washington State officials were unsure what the team records for fewest points or field goals in a half were but said Thursday's totals were the lowest since at least 2001. Arizona officials didn't know if the Washington State marks were an opponent low for any Wildcats' game, including those before McKale was built.
"Our goal all season was to be a top 10 defense," Johnson said. "I think we should push that to a top five and eventually the No. 1 defense in the country, because I think we have the tools to make it happen. This, I guess, is an example of what we can do."
Lacy, who is averaging 18.9 points per game, will also miss Sunday's game at Arizona State.